Ibudilast
Ibudilast is a small molecule drug (molecular weight of 230.3) having the structure shown below.

Ibudilast is also found under ChemBank ID 3227, CAS # 50847-11-5, and Beilstein Handbook Reference No. 5-24-03-00396. Its molecular formula corresponds to C14H18N2O. Ibudilast is also known by various chemical names including 2-methyl-1-(2-(1-methylethyl)pyrazolo(1,5-a)pyridin-3-yl)1-propanone; 3-isobutyryl-2-isopropylpyrazolo (1,5-a)pyridine]; and 1-(2-isopropyl-pyrazolo [1,5-a]pyridin-3-yl)-2-methyl-propan-1-one. Other synonyms for ibudilast include Ibudilastum (Latin), BRN 0656579, KC-404, and MN-166. Its brand name is KetasRTM. Ibudilast, as referred to herein, is meant to include any and all pharmaceutically acceptable salt forms thereof, prodrug forms (e.g., the corresponding ketal), solvates, and the like, as appropriate for use in its intended formulation for administration.
Ibudilast has been widely used in Japan for relieving symptoms associated with ischemic stroke or bronchial asthma. Marketed indications for ibudilast in Japan include its use as a vasodilator, for treating allergy, eye tissue regeneration, ocular disease, and treatment of allergic ophthalmic disease (Thompson Current Drug Reports). US Patent Application Publication No. 2009/0062330 discloses the treatment of progressive neurodegenerative diseases by the administration of ibudilast. This publication generally discloses that ibudilast may be administered in a combination treatment along with an additional agent effective for treating progressive neurodegenerative diseases, but does not provide any guidance on the choice of the additional agent.
Riluzole
Riluzole has the formula:
and is indicated for the treatment of patients with amyotrophic lateral sclerosis (ALS). Chemically, riluzole is 2-amino-6-(trifluoromethoxy) benzothiazole.